#include <stdio.h>
int f(int b[ ][4])
{
	int i,j,s=0;
	for(j=0;j<4;j++)
		{i=j;
		 if(i>2) i=3-j;
		 s+=b[i][j];
		 }
	return s;
}
int main( )
{
	int a[4][4]={{1,2,3,4},{5,6,7,8},{9,10,11,12},{13,14,15,16}};
	printf("%d\n",f(a) );
	return 0;
}